Metering valve for regulating the flow of contaminated fluids

ABSTRACT

A flow metering valve for regulating the flow of fluids contaminated with particulate matter includes a valve housing with a translatable valve member disposed within the housing and space apart from the interior walls of the housing by guide means which minimize the contacting areas of the moving surfaces, substantially reducing the risk of particulate matter being drawn therebetween and seizing the moving parts. Metering ports are unevenly arranged around the housing such that the flow of pressurized fluid through the housing operates to load the valve member into tight engagement with the areas immediately surrounding the metering ports so as to provide substantially zero clearance therebetween, and further aid in prohibiting the intrusion of contaminants between the moving surfaces.

United States Patent 1 1 Cornell 1 Oct. 16, 1973 METERING VALVE FORREGULATING THE FLOW OF CONTAMINATED FLUIDS [75] Inventor: Richard HenryCornell, Marblehead, Mass. [73] Assignee: General Electric Company,

221 Filed: Dec. 20, 1971 211 Appl. No.: 209,693

[52] US. Cl 137/538, 137/537, 137/541,

137/543.2] [51] Int. Cl. Fl6k 15/02 [58] Field of Search 138/46;137/5133,

[56] References Cited UNITED STATES PATENTS 1,074,199 9/1913 Poland251/1'93 1,128,077 2/1915 Taylor 137/538 X 2,085,982 7/1937 Johnson137/538 2,700,394 1/1955 Jay 137/118 2,896,662 7/1959 Thomas 137/5382,934,085 4/1960 Mylander 251/175 X 2,991,972 7/1961 Busby 251/1753,080,885 3/1963 Webster et a1 137/538 X Primary Examiner-Robert G.Nilson Attorney-Edward S. Roman et a1.

[5 7 ABSTRACT A flow metering valve for regulating the flow of fluidscontaminated with particulate matter includes a valve housing with atranslatable valve member disposed within the housing and space apartfrom the interior walls of the housing by guide means which minimize thecontacting areas of the moving surfaces, substantially reducing the riskof particulate matter being drawn therebetween and seizing the movingparts. Metering ports are unevenly arranged around the housing such thatthe flow of pressurized fluid through the housing operates to load thevalve member into tight engagement with the areas immediatelysurrounding the metering ports so as to provide substantially zeroclearancetherebetween, and further aid in prohibiting the intrusion ofcontaminants between the moving surfaces.

8 Claims, 8 Drawing Figures METERING VALVE FOR REGULATING THE FLOW OFCONTAMINATED FLUIDS BACKGROUND OF THE INVENTION This invention relatesto a flow metering valve for operation with fluids contaminated withparticulate matter and more particularly to a flow metering valve forcontinuous operation with contaminated fluids wherein the movingsurfaces of the metering valve are maintained free of particulate matterwithout the addition of a complex wash fluid means for cleansing themoving surfaces.

The invention herein described was made in the course of or under acontract or subcontract thereunder, (or grant) with the Department ofthe Army.

One application for a fuel metering valve may include utilization withina gas turbine engine to accurately meter prescribed amounts of fuel toeach of several nozzles which disperse the fuel within a combustionchamber for burning. Fuel may be metered by flowing fuel through achamber such that the output flow is directed through a metering port,the area of which may be adjusted. A simple, yet highly effective,metering orifice may be formed by two opposing walls, wherein one of thewalls contains a hole or window of predetermined size and the other wallis adapted to slide over the surface immediately surrounding the hole,cooperating therewith to form a metering port. The metering port may befully opened by sliding one of the walls into full offset relation withthe opposing wall, or alternatively the metering port may be fullyclosed by sliding the walls into overlapping relation so as to block theflow of fluid therethrough.

In a working fuel distribution system for gas turbine engines, the fuelis generally contaminated by undesirable particulate matter. Thesecontaminants are drawn between the moving walls of the fuel meteringvalve causing sticking and seizure of such members. Seizure and wearcould be prevented by highly filtering all of the fuel undergoingdistribution; however, this would prevent high flow rates since a filtersmall enough to remove the smallest contaminants would also impose ahigh pressure drop upon the system.

An alternate solution which has been practised in the art involvesdiverting a portion of fuel from the main flow path at a point upstreamof the metering valve. The diverted fuel is then finely filtered toserve as a wash fluid whereupon it is introduced between the slidablewalls of the metering port. The finely filtered wash fuel cleanses thearea intermediate the moving surfaces preventing sticking or seizure ofthe moving parts.

The disadvantages to a finely filtered wash fuel system relate to theadded complexity of what would otherwise be a simple metering valve.Additional hardware in the nature of very fine filters together withconduits for diverting the wash fuel all contribute to increase both theweight and complexity of the metering valve with a correspondingdecrease in reliability.

Therefore, it is an object of this invention to provide a metering valvefor regulating the flow of fluid contaminated by particulate matter,wherein the moving surfaces of the valve are protected against stickingand seizure without diverting and finely filtering a portion of the mainflow for use as a wash fluid.

It is also an object of this invention to provide a simplified meteringvalve for regulating the flow of fluid contaminated by particulatematter wherein the arrangement of the sliding valve member within thevalve housing is sufficient, in and of itself, to prevent particulatematter from drifting between the moving surfaces.

SUMMARY OF THE INVENTION A flow metering valve includes a valve housinghaving a chamber therein, together with inlet means for directing fluidinto the valve chamber and outlet means disposed asymmetrically aroundthe valve housing for directing fluid out of the valve chamber. Atranslatable valve member is included within the valve chamber andspaced apart from the walls of the valve chamber. Guide means areinterposed between the valve member and valve chamber to support thevalve member in spaced apart relation to the valve chamber. Flow throughthe valve chamber is varied by translation of the valve member withinthe valve chamber and the asymmetric arrangement of the valve meansaccommodates loading of the valve member against the area immediatelysurrounding the outlet means.

DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims distinctly claiming and particularly pointing out the inventiondescribed herein, it is believed that the invention will be more readilyunderstood by reference to the discussion below and the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view of the flow metering valve of thisinvention.

FIG. 2a, 2b, 2c, and 2d are cross-sectional views across the line 2-2 ofFIG. 1 showing alternate arrangements for the flow metering valve ofthis invention.

FIG. 3 is a cross-sectional view across the line 33 of FIG. 1.

FIG. 4 is a cross-sectional view of an alternate embodiment of the flowmetering valve of this invention. FIG. 5 is a cross-sectional view ofanother alternate embodiment of the flow metering valve of thisinvention.

DESCRIPTION OF THEPREFERRED EMBODIMENT Referring now to the drawing andparticularly to FIG. 1, there is shown generally at '10 a flow controlor flow metering valve including a valve housing 12 defining a chamber14 therein. The valve housing 12 includes an inlet opening 16 forreceiving an inflow of fuel and an outlet opening 18 for dischargingfuel from the valve housing 12. A movable valve member shown generallyat 20 is retained for longitudinal translation within the vvalve housing12. As may be readily observed from FIG. 2a, the valve housing generallyassumes the shape of a cylinder, and the movable valve member 20generally assumes the shape of a piston which is axially translatablewithin the cylindrical housing. It should be understood, however, thatthe intended scope of invention is not limited to a circularcross-sectional configuration and that the valve and housing couldalternatively be curvilinear or recilinear in cross-section.

' The valve housing 12 includes an outlet metering port 22 through thebottom portion thereof and the slidable valve member covers the meteringport when in the closed position; A compression spring 24 seats withinthe hollow valve member piston 20 and engages a wall 26 of the valvechamber so as to urge the valve member 20 to the closed position. Thevalve member head shown generally at 28 may include a beveledcircumferential flange 30 around the periphery thereof, wherein theflange 30 is made integral to the valve member piston 20. Translation ofthe edge 32 of flange 30 over the metering port 22 determines the exactrate of fuel flow through the flow metering valve 10.

Referring now to FIG. 3 for greater detail of the outlet metering port22 it can be seen that the port includes a neck portion 34 with initialparallel sides 35, 36 and an adjacent portion 38 with diverging sides39, 40. The metering port herein described is conventional and althoughpreferred for the purposes of this invention, it is by no means anessential requirement and other metering port configurations couldalternatively be utilized.

As is readily apparent from FIG. 1. and HG. 2a, the diameter of thevalve member piston 20 is made smaller than the diameter of the valvechamber housing 12. As best seen in FIG. 2a, the valve" housing 12 ismaintained concentric to the valve member piston 20 by threecircumferentially spaced, axial guides-42, 44 and 46 which are formedintegral to the valvehousing 12, and project radially inward into thevalve chamber 14 so' as to intimately engage the axially extending side'surface of the valve member piston 20 and maintain the valve memberpiston for axial sliding motion within the valve housing. The axialguides 42, 44 and 46am preferably spaced apart at equal arcuatedistances thereby evenly distributing the loading forces on each guide.The bottom guide 46 extends a greater circumferential distance than theremaining guides 42, 44 so as to-accommodate the metering port 22 whichextends therethrough. An annular dynamic seal means 50 circumferentiallyextends around the valve member piston 20 and provides for sealingengagement between the outside surface of the valve member piston 20 andthe inside surface of the valve housing chamber 14. The annular seal 50is referred to as a dynamic seal because it rolls upon axial translationof the outside surface of the valve member piston 20 and is, therefore,generally referredto as a rolling diaphragm.

in operation, the metering valve may serve either,

' as a pressurizing valve, a relief valve, or a bypass pressure dropregulating valve. For application as a fuel metering valve in a gasturbine engine, unfiltered fuel or fuel which has previously beenfiltered through a somewhat coarse filter to filter out particles thatmight otherwise clog the valve inlet and outlet passages is directedunder pressure to the inlet port 16 of the valve housing. The fuelenters the valve chamber 14 whereupon, due to the normal closed positionof the metering valve piston 20, the outlet flow of fuel becomesrestricted. The pressure of the restricted fuel within the chamber Meventually increases to compress the spring 24 axially translating thepiston toward the open position.

As previously discussed, particulate matter dispersed within the fueltends to lodge between the moving surfaces of the valve eventuallyjamming the valve movement. The problem has been found to beparticularly acute in the areas immediately surrounding the meteringports where a portion of the high velocity flow of pressurized fuelcreeps between the moving surfaces depositing contaminants therebetween,and eventually causing the moving parts to seize. Previous methods forpreventing this type of jamming in valve mechanisms which metercontaminated fluids involved intricate schemes whereby a portion of themetered fluid had to be diverted and highly filtered. Then the highlyfiltered 'wash fluid was redirected back between the moving surfaces towash away contaminants which may have lodged therebetween. The meteringflow valve of this invention, however, eliminates the necessity ofproviding a separate wash fuel by first minimizing the area of contactbetween the moving surfaces, thereby reducing the likelihood ofparticulate matter lodging therebetween. Second, only a single meteringport is included which operates to provide a substantially zeroclearance between the valve member piston and housing in the area of themetering port, thereby inhibiting dispersion of contaminants between thevalve member piston and housing in this area.

The circumferential width of the guides 42 and 44 is minimized so as topresent as little contacting surface between the guides and piston as ispractically feasible without tending to score the surface of the valvepiston. Also, once the fuel fills the valve chamber the areas aboutwhich the guides42, $4 contact the metering valve piston 20 tend to bequiescent areas of flow, with the main flow and high relative flowvelocities being generally confined to the area directly between theinlet 16 and outlet 18. The fact that the flow in the areas about whichthe guides 42, 44 contact the metering piston 20 tends to be quiescentsubstantially re-' duces the possibility of particles drifting betweenthe moving valve surfaces.

The circumferential width of the bottom guide cannot be made less thanthe width of the metering port 22 which it accommodates. Also, due tothe high relative flow velocities of the fuel passing through themetering port 22, this becomes the area most likely to jam due tocontaminants drifting between the moving parts. However, including onlyone metering port within the housing operates to upset the radialbalance of the metering valve piston during valve operation so that thevalve piston becomes hydraulically loaded against the metering port 22and its associated guide 46. This hydraulic loading provides forsubstantially zero clearance between the moving surfaces immediatelysurrounding the metering port and substantially reduces the tendency forcontaminants and particulate matter to be drawn in around the meteringport as in the case of a multiport, balanced piston type of conventionalmetering valve. The beveled circumferential flange 30 acts to provide animproved pressure recovery on the head of the piston. The hydraulicloading does precipitate an increase in the frictional drag forcesbetween the valve piston and housing; however, the spring force andactuating area of the piston head 28 may be determined independent ofthe metering port area and allow for sufficiently high actuating forcesso as to present no difficulty in overcoming the increased frictionaldrag. As should be readily obvious, the radial extent of the guides 42,44 and 46 must be sufficient to accommodate the largest contaminantparticles. The dynamic seal 50 prevents pressurized fuel from leakingpast the valve member piston thereby preserving the integrity of themetering'mechanism.

It is preferred that the valve should never completely close. Also, thewidth A of the neck portion 34 of the metering port 22 should 'not beless than twice the width of the largest expected contaminant particleso as to reduce the possibility of the metering valve clogging beforeopening. The slopes of the divergent sides 39, 40 of the metering portare preferably maintained at less than 30 to the valve axis whereas 30has been generally found to be the maximum angle which will stillprevent contaminants from lodging between the valve member piston andthe edge of the metering port as the piston closes. The shallow slopeallows the contaminants to be pushed aside by the closing piston.

Although the single metering port as previously described is preferred,it is possible to include more than one metering port and have asatisfactorily operating valve without special provisions for inclusionof a wash fluid to cleanse between the moving surfaces. Referring now toFlG. 2b, there is shown an alternate arrangement wherein first andsecond metering ports 22A, 22B, of the type previously described andshown in H6. 3 pass through guides 64 and 62 respectively. Guide 61) isa supporting member provided to maintain concentricity between the valvemember piston 20 and valve housing 12. As should be readily obvious, theinflow of pressurized fuel to the valve chamber and through the meteringports operates to radially unbalance the piston in the manner previouslydescribed. The valve piston member 20 becomes hydraulically loadedagainst the guides 62, 64 so as to again provide a substantially zeroclearance between the moving parts. The resulting valve friction forthis arrangement however is less than that of HG. 2a assuming identicalflow rates and pressure differentials and further assuming that thecombined areas of the two metering ports equal the area of the singleport of FIG. 20. As becomes immediately obvious, the mechanism common toboth FlG. 2a and FIG. 2b, which makes possible continued operation ofthe metering valve without provision for a wash fluid, relates directlyto the unbalanced or uneven arrangement of the metering ports. it can beseen that even more than two metering ports could be included providedthey were maintained in an asymmetric or uneven arrangement around thevalve member piston surface. However, as the number of metering portsincreases, then the contacting surface areas between moving partscorrespondingly increases with an increasing risk that contaminants willlodge therebetween and jam the moving parts.

Although the guides have been previously described as being integralwith the interior walls of the valve chamber M, it is also possible toform the guides integral with the valve member piston as shown in FIG.2c. Here guides 42, 44', and 46 are formed integral with the valvepiston 20 and the metering port 22 communicates only through the valvehousing 12 so as to accommodate translation of guide 46 thereover. Whenthe guides are formed integral with the valve member piston,anti-rotation means must be provided to prevent the guide 46 fromrotating out of registration with the metering port 22'. Anti-rotationmeans may be provided in the form of axially extending grooves 70, 72 inthe valve housing which engage the ends of the guides 42' and 414respectively. Alternatively, anti-rotation may be provided by some otherarrangement such as a guide pin (not shown).

It is also possible to provide more than one metering port where theguides are formed integral with the valve member piston as shown inFlG.2d wherein first and second metering ports 22A, 22B of the type pre-6 Referring now to FIG. 4, where like numerals refer to previouslydescribed elements, thereis shown an alternate arrangement by which atension spring 24' may be connected between the valve housing 12" andvalve member piston 20 such that expansion of the spring 24 operates toopen the valve. FIG. 5 shows an alternate arrangement whereby the spring24 is eliminated entirely, and the piston is longitudinally translatedby means such as a solenoid or actuator which are not shown. There isalso shown an alternate arrangement for the dynamic seal 50 whereby aconventional annular O ring seal 50' is maintained for sliding motionrelative to the valve housing by interposition between two axiallyspaced and radially extending integral flange members 80, 82.

Although the invention has been escribed in relation to a fuel flowmetering valve as included in a gas turbine engine, it is readilyunderstood to have broader application to any flow metering valvesubjected to a contaminated flow.

It is to be further understood that axially spaced, circumferentialgrooves (not shown) of the type well known to the art may be included ineither the outside surface of the valve member piston or the insidesurface of the valve housing in order to dislodge and remove contaminantparticles in the unlikely event that such particles should jam betweenthe moving surfaces.

Having thus described one embodiment of the invention, what is desiredto be secured by letters patent is as follows:

1. A flow metering valve comprises:

.a valve housing having a chamber therein, together with inlet meansthrough the valve housing for directingfluid into the valve chamber andunevenly arranged outlet means through the valve housing for directingfluid out of the valve chamber;

a valve member disposed for translation within the valve chamber incontinuous spaced apart relation from the walls of the chamber whereinthe valve member includes a head portion tansverse to the Y axis of thevalve translation and the outlet means are unevently disposed around theaxis of valve member translation;

guide means interposed between the valve member and the walls of thevalve chamber to support the valve member in translatable spaced apartrelation to the walls of the valve chamber, wherein the guide means areformed integral to the valve housing and the outlet means communicatesthrough the valve housing and guide means with an opening into the valvechamber which is adjacent the valve member such that translation of thevalve member over the opening regulates the rate of fluid flowtherethrough, and the the uneven arrangement of the outlet means, uponthe introduction of an inlet flow, operates to upset the balance of thevalve member along its axis of translation such that the valve memberbecomes loaded in the direction of I the outlet means providingsubstantially zero clearance between the moving surfaces immediatelyadjacent the outlet means, and substantially reducing the tendency forcontaminants and particulate matter to be drawn in around the outletmeans.

2. The flow metering valve of claim 1 wherein:

the outlet means are unevenly arranged around the valve housing suchthat the flow of pressurized fluid through the housing operates to urgethe valve member into intimate engagement with those guide means throughwhich the outlet means communicates, establishing substantially zeroclearance therebetween so as to inhibit the intrusion of particulatematter between the moving surfaces of the valve member and guide means.

3. The flow metering valve of claim ll wherein:

the valve housing is of a hollow cylindrical shape;

the valve member assumes the general shape of a piston for translationalong the axis of the housing;

the guide means include axial members which extend radially inward fromthe interior of the valve housing chamber and engage the valve piston soas to maintain concentricity between the valve housing and valve piston;

means are included for axially urging the valve member over the openingof the outlet means;

the inlet means are arranged to axially direct the fluid against thehead of the valve piston so as .to urge the valve piston in the axialdirection opposing the urging means thereby controlling the flow throughthe valve;

the outlet means are unevenly distributed around the valve housing suchthat the flow of pressurized fluid through the housing further operatesto upset the radial balance of the valve piston, hydraulically loadingit against those guide means through which the outlet means communicatesestablishing substantially zero clearance therebetween so as to inhibitthe intrusion of particulate matter between the moving surfaces of thevalve piston and guide members; and Y the valve piston further includesan axially extending flange around the periphery of the valve headtogether with a seal disposed between the piston and valve housing toprevent escape of the fluid through other than the outlet means.

4. The flow metering valve of claim 1 wherein the outlet means includesat least two outlet ports.

5. A flow metering valve comprises:

a valve housing having a chamber therein, together with inlet meansthrough the valve housing for directing fluid into the valve chamber andoutlet means through the valve housing for directing fluid out of thevalve chamber;

a valve member disposed for translation within the valve chamber incontinuous spaced apart relation from the walls of the valve chamberwherein the valve member includes a head portion transverse to the axisof valve translation and the outlet means are unevenly disposed aroundthe axis of valve member translation;

guide means interposed between the valve member lates the rate of fluidflow therethrough, and the uneven arrangement of the outlet means, uponthe introduction of an inlet flow, operates to upset the balance of thevalve member along its axis of translation such that the valve memberbecomes loaded in the direction of the outlet means providingsubstantiallyzero clearance between the moving surfaces immediatelyadjacent the outlet means, and substantially reducing the tendency forcontaminants and particulate matter to be drawn in around the outletmeans.

6. The flow metering valve of claim 5 wherein the outlet means areunevenly arranged around the valve housing such that the flow ofpressurized fluid through the housing operates to urge the associatedintegral guide means of the valve member into intimate engagement withthe areas immediate .to the openings of the outlet means establishingsubstantially zero clearance therebetween so as to inhibit the intrusionof particulate matter between the moving surfaces of the valve memberand guide means.

7. The flow metering valve of claim 5 wherein:

the valve housing is of a hollow cylindrical shape;

the valve member assumes the general shape ofa piston for translationalon the axis of the housing;

the guide means include axial members which extend radially outward fromthe outside surface of the valve piston and engage the interior of thevalve housing chamber so as to maintain concentricity between the valvehousing and valve member;

means are included for axially urging the valve member and itsassociated integral guide means over the opening of the outlet means;

the inlet means are arranged to axially direct the fluid against thehead of the valve piston so as to ruge the valve piston and itsassociated integral guide means in the axial direction opposing theurging means thereby controlling the flow through the valve;

the outlet means are unevenly distributed around the valve housing suchthat the flow of pressurized fluid through the housing further operatesto upset the radial balance of the valve piston, hydraulically loadingthe guidemembers against the respective openings of the outlet meansestablishing substantially zero clearance therebetween so as to inhibitthe intrusion of particulate matter between the moving surfaces of theguide members and valve housing;

the valve piston further includes an axially extending flange around theperiphery of the valve head, and

anti-rotational means are provided to inhibit rotation of the valvepiston and its associated integral guide means within the cylindricalhousing together with a seal disposed between the piston and valvehousing to prevent escape of the fluid through other than the outletmeans.

8. The flow metering valve of claim 5 wherein the outlet means includesat least two outlet ports.

a a: a: a

1. A flow metering valve comprises: a valve housing having a chambertherein, together with inlet means through the valve housing fordirecting fluid into the valve chamber and unevenly arranged outletmeans through the valve housing for directing fluid out of the valvechamber; a valve member disposed for translation within the valvechamber in continuous spaced apart relation from the walls of thechamber wherein the valve member includes a head portion transverse tothe axis of the valve translation and the outlet means are unevenlydisposed around the axis of valve member translation; guide meansinterposed between the valve member and the walls of the valve chamberto support the valve member in translatable spaced apart relation to thewalls of the valve chamber, wherein the guide means are formed integralto the valve housing and the outlet means communicates through the valvehousing and guide means with an opening into the valve chamber which isadjacent the valve member such that translation of the valve member overthe opening regulates the rate of fluid flow therethrough, and the theuneven arrangement of the outlet means, upon the introduction of aninlet flow, operates to upset the balance of the valve member along itsaxis of translation such that the valve member becomes loaded in thedirection of the outlet means providing substantially zero clearancebetween the moving surfaces immediately adjacent the outlet means, andsubstantially reducing the tendency for contaminants and particulatematter to be drawn in around the outlet means.
 2. The flow meteringvalve of claim 1 wherein: the outlet means are unevenly arranged aroundthe valve housing such that the flow of pressurized fluid through thehousing operates to urge the valve member into intimate engagement withthose guide means through which the outlet means communicates,establishing substantially zero clearance therebetween so as to inhibitthe intrusion of particulate matter between the moving surfaces of thevalve member and guide means.
 3. The flow metering valve of claim 1wherein: the valve housing is of a hollow cylindrical shape; the valvemember assumes the general shape of a piston for translation along theaxis of the housing; the guide means include axial members which extendradially inward from the interior of the valve housing chamber andengage the valve piston so as to maintain concentricity between thevalve housing and valve piston; means are included for axially urgingthe valve member over the opening of the outlet means; the inlet meansare arranged to axially direct the fluid against the head of the valvepiston so as to urge the valve piston in the axial direction opposingthe urging means thereby controlling the flow through the valve; theoutlet means are unevenly distributed around the valve housing such thatthe flow of pressurized fluid through the housing further operates toupset the radial balance of the valve piston, hydraulically loading itagainst those guide means through which the outlet means communicatesestablishing substantially zero clearance therebetween so as to inhibitthe intrusion of particulate matter between the moving surfaces of thevalve piston and guide members; and the valve piston further includes anaxially extending flange around the periphery of the valve head togetherwith a seal disposed between the piston and valve housing to preventescape of the fluid through other than the outlet means.
 4. The flowmetering valve of claim 1 wherein the outlet means includes at least twooutlet ports.
 5. A flow metering valve comprises: a valve housing havinga chamber therein, together with inlet means tHrough the valve housingfor directing fluid into the valve chamber and outlet means through thevalve housing for directing fluid out of the valve chamber; a valvemember disposed for translation within the valve chamber in continuousspaced apart relation from the walls of the valve chamber wherein thevalve member includes a head portion transverse to the axis of valvetranslation and the outlet means are unevenly disposed around the axisof valve member translation; guide means interposed between the valvemember and the walls of the valve chamber to support the valve member intranslatable spaced apart relation to the walls of the valve chamber,wherein the guide means are formed integral to the valve member and theoutlet means communicates through the valve housing with an opening intothe valve chamber which is adjacent the guide means such thattranslation of the valve member and its associated integral guide meansover the opening regulates the rate of fluid flow therethrough, and theuneven arrangement of the outlet means, upon the introduction of aninlet flow, operates to upset the balance of the valve member along itsaxis of translation such that the valve member becomes loaded in thedirection of the outlet means providing substantially zero clearancebetween the moving surfaces immediately adjacent the outlet means, andsubstantially reducing the tendency for contaminants and particulatematter to be drawn in around the outlet means.
 6. The flow meteringvalve of claim 5 wherein the outlet means are unevenly arranged aroundthe valve housing such that the flow of pressurized fluid through thehousing operates to urge the associated integral guide means of thevalve member into intimate engagement with the areas immediate to theopenings of the outlet means establishing substantially zero clearancetherebetween so as to inhibit the intrusion of particulate matterbetween the moving surfaces of the valve member and guide means.
 7. Theflow metering valve of claim 5 wherein: the valve housing is of a hollowcylindrical shape; the valve member assumes the general shape of apiston for translation along the axis of the housing; the guide meansinclude axial members which extend radially outward from the outsidesurface of the valve piston and engage the interior of the valve housingchamber so as to maintain concentricity between the valve housing andvalve member; means are included for axially urging the valve member andits associated integral guide means over the opening of the outletmeans; the inlet means are arranged to axially direct the fluid againstthe head of the valve piston so as to urge the valve piston and itsassociated integral guide means in the axial direction opposing theurging means thereby controlling the flow through the valve; the outletmeans are unevenly distributed around the valve housing such that theflow of pressurized fluid through the housing further operates to upsetthe radial balance of the valve piston, hydraulically loading the guidemembers against the respective openings of the outlet means establishingsubstantially zero clearance therebetween so as to inhibit the intrusionof particulate matter between the moving surfaces of the guide membersand valve housing; the valve piston further includes an axiallyextending flange around the periphery of the valve head, andanti-rotational means are provided to inhibit rotation of the valvepiston and its associated integral guide means within the cylindricalhousing together with a seal disposed between the piston and valvehousing to prevent escape of the fluid through other than the outletmeans.
 8. The flow metering valve of claim 5 wherein the outlet meansincludes at least two outlet ports.